Add colored pellets to your faucet to turn the water any color for a short time. Martha has detailed instructions here.
Here is the part that saves you a trip to the store: Make your own color tablets! Here are the steps (all measurements are approximate):
- Take precautions to protect your hands and workspace from staining. I would use plastic gloves and waxed paper.
- Find a microwave safe dish, preferably one that is stain resistant!
- Add 1 Tbs baking soda.
- Squeeze in 5 drops of food coloring.
- Mix with fork to combine. Keep mixing, it takes a minute to distribute well.
- Press your mixture into the bottom of the dish with the back of a spoon, adding a few drops of water if needed. Take care not to make it runny, however. The water will boil in the next step and splatter your microwave. I promise!)
- Put in microwave for 20-30 seconds, or until dried into chalk-like chunks.
Another one from Martha. Switch your family's dresser contents, making it a scramble to find the right drawer. This might also be funny with bathroom supplies such as toothpaste and hairstyling products.